I could invent you could invent she could invent we could invent you could invent they could invent
V-ing form
I could be inventing you could be inventing she could be inventing we could be inventing you could be inventing they could be inventing
Perfect
I could have invented you could have invented she could have invented we could have invented you could have invented they could have invented
V-ing perfect
I could have been inventing you could have been inventing she could have been inventing we could have been inventing you could have been inventing they could have been inventing
Negation
Simple form
I couldn't invent you couldn't invent she couldn't invent we couldn't invent you couldn't invent they couldn't invent
V-ing form
I couldn't be inventing you couldn't be inventing she couldn't be inventing we couldn't be inventing you couldn't be inventing they couldn't be inventing
Perfect
I couldn't have invented you couldn't have invented she couldn't have invented we couldn't have invented you couldn't have invented they couldn't have invented
V-ing perfect
I couldn't have been inventing you couldn't have been inventing she couldn't have been inventing we couldn't have been inventing you couldn't have been inventing they couldn't have been inventing
Interrogative form
Simple form
could I invent? could you invent? could she invent? could we invent? could you invent? could they invent?
V-ing form
could I be inventing? could you be inventing? could she be inventing? could we be inventing? could you be inventing? could they be inventing?
Perfect
could I have invented? could you have invented? could she have invented? could we have invented? could you have invented? could they have invented?
V-ing perfect
could I have been inventing? could you have been inventing? could she have been inventing? could we have been inventing? could you have been inventing? could they have been inventing?
Interro-negative form
Simple form
couldn't I invent? couldn't you invent? couldn't she invent? couldn't we invent? couldn't you invent? couldn't they invent?
V-ing form
couldn't I be inventing? couldn't you be inventing? couldn't she be inventing? couldn't we be inventing? couldn't you be inventing? couldn't they be inventing?
Perfect
couldn't I have invented? couldn't you have invented? couldn't she have invented? couldn't we have invented? couldn't you have invented? couldn't they have invented?
V-ing perfect
couldn't I have been inventing? couldn't you have been inventing? couldn't she have been inventing? couldn't we have been inventing? couldn't you have been inventing? couldn't they have been inventing?